Current-measuring arrangement



Patented .May 19, 1925.

UNITED STATES PATENT OFFICE.

RALPH E. PIERCE, OF LARCHMONT, NEW YORK, ASSIGNOR T0 AMERICAN TELEPHONE AND TELEGRAPH GOMFANY, A CORPORATION OF YORK.

CURRENT-MEASURING ARRANGEMENT.

Application filed June 3, 1922. Serial No. 565,589.

To aZZ whom it may concern:

Be it known that I, RALPH E. Prnnon, a citizen of the United States, residing at Larchmont, in the county of \Vestchester and State of New York, have invented certain Improvements in Current-Measuring Arrangements, of which the following is a specification.

This invention relates to an improvement in means and arrangements for measuring currents in telegraph circuits.

It is often the practice to include in the telegraph apparatus at a station a current measuringdevice, such as a mil-ammeter, to indicate the magnitude of the currents transmitted over the circuit to determine whether the telegraph apparatus at the station will function properly, or to determine the condition of balance in the circuit. When the mil-ammeter has been thus utilized in a metallic telegraph circuit, it has heretofore been the practice to connect the operating windingof the mil-ammeter into only one side of the circuit. Under such conditions, particularly when several telegraph circuits are supplied from common battery and operate with full commutation, i. e. double pole changers, it has been found that the true balance of the currents in the relay windings will not always be indicated,for reasons which will be pointed out in detail hereinafter. The same condition might also exist in cases of half commutation with double battery. Accordingly, this invention provides a double differentially wound mil-ammeter with the moving element of the mil-ammeter controlled by windings located in each side of the telegraph circuit. It has been found that with. the arrangements of the invention, a true indication of the currents may be obtained under all the circuit conditions which in practice may be met and the variable results and false readings of former arrangements may be obviated. Other features and objects of the invention will appear more fully hereinafter.

The invention may be more fully understood froin the following description to gether with the accompanying drawing, in

the Figures 1, 2, 3 and 4 of which are illustrated, the arrangements of the invention. In Fig. 1 is illustrated one of the prior ways in which a mil-ammeter could be connected into a telegraph circuit. manner in which the mil-ammeter is connected into the circuit in accordance with the principles of this invention. In Fig. 3 is shown a circuit diagram embodying the arrangements'of the invention, while in Fig. 4' is shown a schematic diagram illustrating the principles of operation of the invention.

Similar reference characters have been utilized to denote like part-s in the figures of the drawing.

In Fig. 1 is shown a metallic telegraph line L terminating in a balancing network Included in the line L are the windings r of a receiving relay- Connected into one side of the line in the manner shown would be the winding A of a mil-ammeter. Conductors are also illustrated leading to a sending circuit. Such a provision of a milammeter with a single winding connected into one side of the line only illustrates prior arrangements which have proven unsatisfactory in respect to reliability of reading under various circuit conditions, as will be pointed out hereinafter. In Fig. 2 are shown the improved arrangements of the invention, which include the metallic telegraph line L vterminating-in a balancing network N and including the relay windings r. Thereare also shown conductorsleadingto a sending c rcuit. Connected into each side of the telegraph line. as shown, would be the windings A and A of the meter. These windings are differentially arranged and together operate to control the moving element of the mil-ammeter. With this arrangement a true measurement of the telegraphic currents may be obtained under the various circuit conditions met in practice, as will appear hereinafter.

In Fig. 3 is illustrated in more detail a circuit diagram of the arrangements of the invention. In this figure are two pairs of lines 1, 2 and 3, 4 interconnecting stations at X and Y. Each pair of lines constitutes a metallic circliit and both are supplied from Fig. 2 shows the a common battery source, such as B and B.

trolled'by the polar relays 17,17, 17 and 17 which are operated by the sending circuits and apparatus in a well known manner. The conductors 1 and 2-terminate at station X in network 5 and the windings 9 of a receiving relay. Connected into each of the, conductors 1 and 2 between the relay windings 9 are the differential windings A, and A, of a mil-ammeter. At station FY conductors 1 ,and 2 terminate in relay windings 10 and the network'7. Differential milammeter windings are also provided thereat as shown. Conductors 3 and i likewise terminate in network '6 and receiving relay windings 11 and there are provided "the mila'mmeter windings A vand A At station Y conductors Sand 4 terminate in relaywindings 12 and the network 8" and there are also provided differential Inil-ammete r windings thereat. Other metalliccircuits might in'like manner'be connected tofthe common batteries B and B and thus utilized to interconnect stations X and'Y.

In Fig. 1 is Sl1O W11iL diagram illustrating 'schen'latically' the principles of operation of The telegraph conductors '1 and 2 are shown terminating at stations X and Y in the network circuits 5 and? and the relay windings land 10, while the conductors 3 .and l terniinateat stations X and Yinfth-e "7 'and8findividually would be 2B. The electromotive "force of each of thebatteries B and Bis termed E. At station Y one of -tl1 econtacts of the double pole changer '14 is shown inan open position. All'the contacts of the other pole changers maybe ,as-

sumed to'be closed.

:The principles vof operation of {the arrangements ofthe lnvejntion are as follows.

Let itbe assumed that the contact of the "double pole changer 14 i-nIlig. 4 is closed, or,

in other words, thatall (if the contacts o'f'the "double pole changers are closed. Let the current in the circuits 1, 2, 3, 4, 5, 6,7. and 8 be; termedrespectivelyl I 1 1 1 ,1 I,

The current in differential winding A equals Fronr the above it will heseen. that with all of thepole changer cont'acts closedythe current in each of the windings A i-and :A, will 'be the same, or

Accordingly, evhen all of the pole changer --co1itac'ts-are-closed, one of'the windings A or A, --migh-t wellib'e -omitted, and a-single winding mil-amm-e'ter -'with a winding in only one side oftheli'n'e' might be used, as 1n former arrangements. A true readingwoul'd 'be obtained with such a device, 1t 1s -adniitted, when all of the contacts were closed.

Now .let it-heaSsun'Iedthat afteran op- A eration of. the pole changers one of the co n ta c-tslagged-behind "the others 01 remained open, such as is illustrated by the open contact ot polechanger 141 01 Fig. 4. ln other words, assume a condition whereall of' the vipole changercontacts were closed except one ofrthc'm, (as .shown. N ow I V 1 ,R +R/2 I BE 2* 4 5 E I5 I6 5 L 1-8 NOW th current, in the; differentialv winding V g E ;E .5jE A141" I5 ".3? ,m ea

and the current in the differential winding w 4 E, E E AZ=IZ I5 l heeurrentintheinitammeter would be i11 v 'dica'ted by E a 6R 6R R From the above it will be seen that the our rent in A is not the same as the current in A when one of the contacts is open as It may thus be seen that if only one winding were used, a wide Variation in reading might be obtained, depending upon which side of the line this winding was inserted. Accordingly, by utilizing two differential windings, one in each side of the line, such false reading may be obviated and a true reading of the current obtained for all eircuit conditions.

lVhile the invention has been illustrated in certain specific arrangements which are deemed desirable, it is understood that it is capable of embodiment in many and widely varied forms without departing from the spirit of the invention as defined in the appended claims.

hat is claimed is:

1. A telegraph circuit including a pair of line wires, and a current measuring device comprising a movable indicating element controlled by differentially arranged windings, said windings being included in opposite sides of said telegraph circuit.

2. A plurality of metallic telegraph circuits adapted full commutation, and milammeters associated with each of said circuits, each of said mil-ammeters comprising a movable indicating element controlled by differentially arranged windings located serially in opposite sides of each of said telegraph circuits. I

3. In a telegraph system, a line including a pair of line wires, a balancing network therefor, a receiving relay comprising windings in each of said line Wires and windings in the connections extending to said balancing network, a current measuring device ineluding a movable indicating element controlled by differentially arranged windings, each of said differential windings being included between the receiving relay windings in opposite line Wires, and a transmitting circuit to neutral points-with respect to the windings of said receiving relay and with respect to said diflerential windings.

In testimony whereof, I have signed my name to this specification this 2nd day of June 1922.

RALPH E. PIERCE. 

